Pathology Core The Pathology Core will be used by all of the projects of the Center. It will coordinate and provide services for specimen collection, clinical hematology and serum chemistry, tissue fixation and processing, preparation of histology specimens, and histopathologic analyses. For Project 5, the core will collect and process tissues and body fluids under standard operating procedures (SOPs) from animals designated for safety assessment of potential therapeutics using Good Laboratory Practices (GLP) as outlined by the FDA. For Projects 2, 3, and 5, pathogenesis of sulfur mustard-induced acute and chronic lung injury will be investigated. Specimens obtained by the core in these projects may be analyzed by clinical pathology and histopathology as well as by methods outlined in Project 1 for identification of potential targets of therapeutic intervention. Specific methods for study will include: 1) routine necropsy procedures for dogs and rodents, 2) full-set tissue collection for histopathologic evaluation of target organ and sytemic toxicity, 3) routine hematology, serum chemistry, and urinalysis for toxicity assessment, 4) bronchoalveolar lavage (BAL) for analysis of cells and fluid, 5) constant pressure inflation-fixation of lungs for stereology/morphometry, 6) hematoxylin and eosin (H&E) staining of paraffin embedded tissues, 7) special stains for mucus (alcian blue and periodic acid-Schiff) and fibrous tissue (Masson's trichrome), 8) morphometry of mucous cell hyperplasia and hypertrophy in the conducting airways, and 9) morphometry for pulmonary emphysema and fibrosis. Additional procedures may include freezing of tissue for biochemistry, molecular biology, and proteomics (Project 1);cryomicrotomy;immunohistochemistry for any antigen in frozen or paraffin-embedded tissue sections;and in situ hybridization for mRNA detection.